Photocopy heater circuit



Feb.24, 1970 l D.w.svc;HENDERL.'|Nc v3,497,300v

PHoTocoPY HEATER CIRCUIT Filed Sept. 6. 1967 INVENTOR. Dick wilhelm Schenderling ATTORNEY United States Patent 3,497,300 PHOTOCOPY HEATER CIRCUIT Dick Wilhelm Schenderling, Maassluis, Netherlands, assignor to GAF Corporation, New York, N.Y., a corporation of Delaware Filed Sept. 6, 1967, Ser. No. 665,878 Int. Cl. G03b 27/30 U.S. Cl. 35S- 106 5 Claims ABSTRACT OF THE DISCLOSURE l This invention relates to photocopy apparatus, more particularly it relates to photocopy apparatus having a control mechanism operative to couple an exposure unit to a source of power at controlled intervals and more specifically it relates to photocopy apparatus wherein said control mechanism is characterized by a thermostatic switch operable in response to a particular temperature in the developing tank of the photocopy apparatus to couple the exposure unit to a source of power.

In accordance with the present invention, the copying apparatus includes a printing section having an electric lamp, preferably a fluorescent lamp, and a developer section for generating an ammonia vapor from an ammonia solution by immersing a heater element therein. The heater element is electrically connected in series with the lamp and a switch, preferably a thermostatic switch, is arranged to short circuit the lamp until the ammonia solution is suiiciently hot to generate suicient vapor to develop exposed sensitized material presented thereto. Thus, the lamp will not light, and no copies can be produced, until suicient ammonia vapors are present in the developer section. However, at the preset temperature, the thermostatic switch connected across the lamp opens, and the heater resistances will now function as lamp ballast to permit the fluorescent print lamp to light, whereby the photocopy machine is operational to produce copies from an original.

One of the objects of the invention is to provide a control mechanism of the above nature that is characterized by simplicity and operational reliability over an extended period of use.

Another object of the invention is to provide such a mechanism that is inexpensive to manufacture and easy to install in photocopy apparatus.

Still another object of the invention is to provide a control mechanism which prevents exposure of copy material until the developing apparatus is operational.

These and other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings in which:

FIG. 1 is an elevational view of the photocopy apparatus; and

FIG. 2 is an electrical circuit diagram in accordance with the present invention.

Referring now to the drawings, wherein like reference Fice characters designate like to corresponding parts throughout the several views, there is shown in FIG. l a photocopy apparatus generally designated as reference numeral 1 having a printing section and a developing mechanism section designated as reference numerals 2 and 3, respectively. As shown the printing section 2 includes a glass cylinder 4 in which a fluorescent light source 5 is mounted. The developing section 3 includes a container 6 having a supply of liquid ammonia 7 which is adapted to be vaporized by a heater element 8. A blower (not shown) driven by an electric motor 12 distributes the ammonia vapor in developer section 3. The foregoing components of the photocopy machine have been described and illustrated generally because they are related only generally to the invention claimed. They are well known in the art and may be of any suitable construction.

Referring now to the control mechanism illustrated in FIG. 2, it will be seen that the heater element 8 is connected serially with the fluorescent light source 5 (which is bridged by a starter S in the usual manner). Their common junction 15 connects to a rst switch contact 13' of a thermostatically operated switch 13, located in heat transfer relation with respect to heater 8 in container 6, as indicated by the dashed line and arrow to the heater 8. When the temperature sensed by the thermostatic switch is cold, connection is established with lirst contact 13.

Thus, in operation, upon irst closing of a main switch 9, current is connected from an electrical energy source 11 over the top line 11 through the heater element 8, junction 15, contact 13' of switch 13 to the bottom line 11". After a predetermined temperature has been reached, as determined by the conductivity of heat to switch 13, thermostatic switch 13 will snap over and make contact with a second or further contact 13 connecting the bottom line 11" through motor 12 to the top line 11", thus starting the blower. Simultaneously the short circuit previously established across light source 5 by connection of contact 13 is removed, and a circuit will be established from the top line 11 through heater element 8, junction 15, light source 5 to the bottom line 11". Thus, heater element 8 will now act as a ballast for the iluorescent light source and the total current through the circuit including the heater will be reduced by the resistance of the light source 5, whereby the temperature within container 6 will not rise further but rather will be maintained at the predetermined level, which is sutlicient for generation of ammonia fumes or vapors for developing of exposed sensitized material. Thus, automatically and without further apparatus, an interlock is provided, preventing illumination of the light source unless suicient vapor or fumes to develop exposed sensitized material are present.

The switch 13 may, of course, be a timer which is activated by the closing of main switch 9 to contact 13' for a predetermined time after which it will snap over to contact 13".

After the copying operation is completed, i.e. when the main switch 9 is opened, rapid cooling olf of the apparatus will occur inasmuch as blower 12 remains coupled to the electrical energy source 11 until the temperature has dropped to a point where the switch 13 snaps over to contac-t 13.

It should also be understood that the foregoing relates to only a preferred embodiment of the invention, and that tized paper exposed to a printing light, the improvement comprising: l

an exposure section having a printing electric lamp; a developing chamber having a heating means for increasing the temperature in said chamber; said lamp and heater means being serially connected across said power source and having a common junction therebetween; and automatic switch means adapted to be coupled to said power source and responsive thereto to couple said common junction to said heater means whereby said lamp is short circuited and when a physical parameter is changed, said switch means being responsive to said changing physical characteristic to decouple said common junction from said source of power such that said lamp is permitted to operate with said heater means functioning as a ballast thereto and the current through said heater means being reduced by the additional lamp resistance such that said heater 4means, maintains a predetermined temperature in said chamber. 2. Apparatus as recited in claim 1 wherein said lamp is a fluorescent lamp.

3. Apparatus as recited in claim 1 wherein said switch means includes a iirst contact coupled to said common junction and a further contact which is coupled to said source of power when said rst contact is decoupled therefrom and a blower in circuit with said further contact.

4. Apparatus as recited in claim 1 wherein said physical characteristic is the temperature in said chamber.

5. Apparataus as recited in claim 1 wherein said switch meansis a thermostatic switch located in heat transfer relation to said heater means.

NORTON ANSHER, Primary Examiner R. L. MOSES, Assistant Examiner U.S. C1. X.R. 95-89 

